Method and apparatus for making stereotype-plates.



J. M. DOW.

METHOD AND APPARATUS FOR MAKING STEREOTYPE PLATES.

APPLICATION FILED MAY 0. 1911.

I 1,022,067, v Patented Apr. 2, 1912.

2 SHEETSBHBET 1.

44K J. J

J. M. DOW. METHOD AND APPARATUS FOR MAKING STERBOTYPE PLATES.

APPLICATION mum MAY 6. 1911.

1,022,067. Patented Apr. 2, 1912.

2 SHEETS-SHEET 2.

6 644%. J, u 1..., I

COLUMBIA PLANOORAPH CO" WASHINGTON, D. C.

UNITED STATES PATENT OFFICE.

JAMES MARSHALL DOW, OF EVERETT, MASSACHUSETTS.

METHOD AND APPARATUS FOR MAKING STEREOTYPE-PLATES.

To all whom it may concern:

Be it known that I, JAMES MARSHALL Dow, a citizen of the United States,and resident of Everett, in the county of Middlesex and StateofMassachusetts, have invented new and useful Improvements in Methodsand Apparatus for-Making Stereotype-Plates, of which the following is aspecification.

This invent-ion relates to the making of stereotype plates, and consistsin a new method of casting such plates and a new apparatus therefor, bythe use of which air holes or blow holes, as they are usually called, inthe face of the plate, will be eliminated.

The problem of casting stereotype plates without air holes in the faceof the plate has long engaged the attention of the makers of stereotypeplates and casting boxes therefor, but has hitherto remained withoutsatisfactory solution; and no method or apparatus thus far employed hasmade it possible with certainty to produce stereotype plates without airholes in the face. The precise cause of such air holes is somewhatobscure, but I believe them to be due to the fact that under presentpractices when the molten metal is introduced into the casting boxes,whether by pouring it or forcing it in under hydraulic or otherpressure, it has to flow either downwardly 01' laterally, or both, intothe depressions or indentations of the matrix, which is in the lowerside of the inclined casting box. When the metal is poured in from thetop it has to flow over the whole surface of the matrix to the bottom ofthe box, and in so doing tends to cascade over the uneven surface of thematrix, entrapping small bubbles of air between the metal and the matrixsurface. The same result occurs when the box is supported in verticalposition. The metal hardens almost instantly and before the air bubbleshave any chance to rise and work their way out, so that the surface ofthe finished plate is almost invariably pitted or pock marked by the airholes. Similarly, should the molten metal be forced into the casting boxat the bottom by hydraulic or other pressure, the entrance of the metalwould be very rapid, and as it flowed upwardly over the surface of thematrix and laterally into the depressions therein, it would entrapbubbles of air, which would Specification of Letters Patent.

Application filed May 6, 1911.

Patented Apr. 2, 1912.

Serial No. 625,618.

leave air holes in the face of the plate, just as when the metal ispoured in from the top. Thus, with the matrix in the lower side of theinclined box, or at one side of a vertically supported box, the metalflows over the surface of the matrix, whether it be introduced from thetop or the bottom, and also has to flow laterally to fill theindentations of the matrix; and as the metal moves rapidly it tends tobridge and confine air spaces as it cascades from one projection of thematrix to the next, instead of wholly filling the matrix and driving outthe air before it. lVhether this is the true explanation of the cause ofthe formation of the air bubbles or not, the foregoing conditions areavoided by my method, and stereotype plates made according to my methodare wholly free from air holes in the face. WVith my method instead ofcansing the metal to flow downwardly or laterally into the indentationsof the matrix, or over the surface of the matrix, I introduce the metalinto a casting box having an inclined and overhanging matrix surfacewith the result that the metal rises against the matrix surface and intothe indentations without downward or lateral flowing.

For performing my new method I have also invented certain improvement-sin stereotype casting boxes, illustrated in the accompanying drawings,wherein- Figure 1 is a side view of the box for casting flat stereotypeplates; Fig. 2 is a longitudinal, central section, enlarged and partlybroken away, of the casting bo-x shown in Fig. 1; Fig. 3 is an elevationof said casting box viewed from the right of Fig. 1; Fig. 1 is a crosssection through the middle of said casting box; Fig. 5 is a longitudinalsection of the upper end of a casting box for making a curved stereotypeplate; Fig. 6 is an elevation of the upper end of the lower or smoothsection of the casting box shown in Fig. 5; and Fig. 7 is a crosssection of said curved casting box.

Referring first to Figs. 1 to 4 of the drawings, A represents thesupporting frame provided with trunnion bearings a.

a represents a notched support for one end of the casting box, while thebox and matrix are beingassembled, said support a being pivoted to theframe at a and operated in the usual way by the handle a; and arepresents a bow-shaped bar secured transversely of the frame A belowthe bearings a.

The casting box consists of the box-sec tion B and the separable coversection B. Trunnions b, secured to the sides of the boxsection B, aresupported in the bearings a. In the construction herein shown saidtrunnions project from the yoke-shaped frame 12 which is bolted at itsends to the sides of the box section, and extends across the casting boxto support the clamping screw 6 by which the cover section B is clampedto the box section B. The ends of the bar o secured to the cover sectionB, engage slots 6 in ears b on the box-section B, and form a pin andslot connection between the two sections of the casting box.

The casting box is shown in the drawings in operative position forperforming my new method. When the box and the matrix are beingassembled, the box is swung on its pivot bearing to substantiallyhorizontal position with the box-section B lowermost. The end of the boxwill then rest on one of the notches of support a. The matrix at is thenplaced face upward in the box-section B, the bearers c are placed on themargins of the matrix in the usual way and a sheet of paper 0 is placedon top of the bearers. Another piece of paper a is preferably placedover the end of the matrix which will be uppermost in operation, toprevent any metal from running under the matrix. The cover B is thenclosed and clamped against the bearers. By lifting handle a the supporta will be moved from under the end of the casting box, permitting thatend to swing downward, and the casting box may be swung on its pivotbearings, past the vertical position, into an inclined position as shownin the drawings with the matrix surface overhanging the opposed smoothsurface of the cover section. The transverse bar a engages the outerside of the box-section, and acts as a stop to arrest and hold thecasting box in its proper inclined position with the matrix surfaceoverhanging the smooth surface. The metal is then introduced into thebox, as by pouring into the upper end of the box, and flows down thesmooth surface of the cover section, rising against the overhangingmatrix surface and rising into the indentations, without flowing downover the surface of the matrix or flowing laterally into theindentations. The rising surface of the metal drives out all air beforeit and wholly fills the matrix surface, resulting in a stereotype plate,when hardened, free from air holes in its surface.

The casting box shown in Figs. 5 to 7 differs from that alreadydescribed only in that the box-section B is curved or cylindrical inform, the matrix on being placed on the concave side, and the coversection B is similarly curved, its convex side forming the smoothsurface of the stereotype plate.

The mounting, manipulation, and operation of the two forms of castingboxes are substantially the same, one forming a flat plate and the othera curved plate. One section of each box is beveled or flared outwardlyto form a trough-like or funnel-like entrance for the metal. In the flatbox the box-section is beveled as shown at (Z and in the curved box itis the cover section which is made with the trough d.

The precise angle at which the overhanging matrix surface stands when inoperative position is not material. It is essential that it be swungpast the vertical position, that is, to an inclined position at an angleexceeding ninety degrees with a horizontal plane, but less than onehundred and eighty degrees with such plane. In practice I have obtainedgood results by bringing the overhanging matrix surface to an angle ofsubstantially one hundred thirty-five degrees with its originalhorizontal position, but it will be understood that some variation fromthat angular position may be allowed without departing from myinvention.

I claim 1. The method of casting a stereotype plate consisting inintroducing molten metal 95 into a casting box having a matrix surfacewhich is inclined and overhanging throughout its whole extent, wherebythe metal will rise against the matrix surface and into the indentationsthereof without flowing over any part of the matrix surface.

2. A stereotype casting box, comprising two opposed walls spaced apart,said box being supported in an inclined position, and a matrix securedagainst the upper of said opposed walls, the inclined matrix surfacethroughout its whole extent overhanging the lower wall surface, wherebythe molten metal will flow over the lower surface of the box and riseagainst the matrix surface without flowing over any part of the matrixsurface.

3. A stereotype casting apparatus, comprising a supporting frame, acasting box having a box-section and a separable cover 1 section, thebox-section being pivotally mounted on said frame and adapted to containa matrix, said box being revoluble to an inclined position at an angleexceeding ninety degrees with a horizontal plane, whereby thebox-section will overhang the cover section.

4. A stereotype casting apparatus, comprising a supporting frame, acasting box having a box-section and a separable cover section, thebox-section being pivotally mounted on said frame and adapted to containa matrix, said box being revoluble to an inclined position at an angleexceeding ninety degrees with a horizontal plane,

whereby the box-section will overhang the cover section, and a stop toarrest and hold said box in such inclined position.

5. A stereotype casting apparatus, comprising a supporting frame, acasting box having a box-section and a separable cover section, thebox-section being pivotally mounted on said frame and adapted to containa matrix, said box being revoluble to an inclined position at an angleexceeding ninety degrees with a horizontal plane,

whereby the box-section will overhang the cover section, and a barsecured transversely of said frame, adapted to engage said box to arrestand hold said box in such inclined 15 position.

Signed by me at Boston, Massachusetts, this second day of May 1911.

JAMES MARSHALL DOW. Witnesses:

ROBERT CUsHMAN, CHARLES D. WOODBERRY.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents,

Washington, D. 0.

